Device for producing stimulated emission of infrared rays (irasers)



DEVICE FOR PRODUCING STIMULATED EMISSION 0F" INFRARED RAYS (IRASERS) Filed Sept. 10, 1955 Feb. 3, 1970 w. J. WITTEMAN ETAL I 3,493,892

INVENTORJ WILHEL MUS LWUTEMAN RICHARD BLEEKRODE BY M I? I AGENT United States Patent 3,493,892 DEVICE FOR PRODUCING STIMULATED EMIS- SION OF INFRARED RAYS (IRASERS) Wilhelmus Jacobus Witteman and Richard Bleekrorle, Emmasingel, Eindhoven, Netherlands, assignors, by mesne assignments, to US. Philips Corporation, New York, N.Y., a corporation of Delaware Filed Sept. 10, 1965, Ser. No. 486,385 Claims priority, application Netherlands, Sept. 23, 1964, 6411059 Int. Cl. I-Ils 3/02 US. Cl. 331-945 3 Claims ABSTRACT OF THE DISCLOSURE A laser device including a discharge tube for producing a continuous laser discharge and being provided wlth a continuous flow of water vapor.

between 28 and 119,11. with maximum energies of 1 W.

However, a disadvantage of this arrangement is that high power and high voltage are required.

The primary object of this invention is to provide a device in which stimulated infrared emission can be btained by using more moderate power and voltage supplies. In carrying out this object in accordance with the invention, a device for producing stimulated infrared emission by means of an electric discharge in water vapor is provided wherein the pressure of the water vapor range from a few tenths of a millimeter up to a maximum of 1 mm. Hg. The optical resonator has a noble metal cover providing the conventional mirrors for b0unding the discharge space and a window in said cover for the emanating beam. It has been found that with pressures of more than about 0.8 mm. the output level of the stimulated emission drops drastically. The voltages to be employed with said low pressures are less than kv., even with a discharge space of a few meters and the power to be supplied on an average remains below 1 kw.

Pulse oriented production of the stimulated infrared emission in a device according to the invention requires a discharge length of not more than about 1 meter. A continuous production requires a discharge length of a few meters (3 or more) in flowing water vapor. In the case of stationary water vapor the stimulated emission ceases after a few tenths of a second, while H- and OH- "ice Referring to the drawing reference numeral 1 designates a glass tube having a length of 4 meters and a diameter of 32 mms. Mirrors 2 having a radius of curvature of 410 cms. are secured to the ends in a vacuum-tight manner. The mirrors have a vapor deposited gold layer 3 of a thickness of about 300 AB. One of the mirrors has an opening 4 of a diameter of 1 mm., behind which a 1 mm. thick window 5 of silicon is arranged. The tube 1 is provided with short side tubes 6 holding the discharge electrodes 7. The tube is surrounded by a heating element 8 for thermal adjustment. The water vapor is supplied from the stock of water 9 contained in a Dewar vessel along with a mixture of alcohol and liquid nitrogen. The pressure gauge space 10 is closed by control-cock 11 and 11A. The water vapor is conducted away through the control-cock 12 by the pump 13. The burning voltage of the tube is 7 kv. with a continuous direct current of to ma. and a pressure of the flowing water vapor of 0.2 mm. at room temperature. From the window 5 a coherent infrared beam can be obtained with a total power of 0.5 to 1.0 mw. The wavelengths concerned lie between 28 and 119 With a different tube having a length of 1 meter and mirrors of a radius of curvature of 1036 mms. a pulsatory' operation on a frequency of 10 c./ s. had a pulsatory voltage of S kv. and an average current of 40 ma. Also in this case the above-mentioned lines were obtained. The water vapor may be stationary.

What is claimed is:

1. A device for producing a continuous stimulated infrared emission comprising a discharge tube, means for maintaining a continuous flow of water vapor through said tube, means for producing a continuous electric discharge in said tube, and means for maintaining the pressure of said water vapor within said tube in the range encompassing about 0.2, mm. Hg to 1.0 mm. Hg wherein the discharge length of said tube is not less than about 3 meters.

2. The combination of claim 1 wherein the pressure of said water vapor is 0.2 mm. Hg.

3. A laser device comprising a discharge tube containing water vapor and having a discharge length of one meter or less, first and second noble metal coated mirrors secured to the ends of said tubes, one of said mirrors having an opening therein, a silicon window positioned behind said opening, a pair of discharge electrodes couples to said tube for producing a pulsatory electric discharge in said tube so as to provide a coherent continuous, stimulated beam, and means for maintaining the pressure of said water vapor within said tube in the range encompassing about 0.2 mm. Hg to 1.0 mm. Hg.

References Cited Patel Properties of Lasers, Lasers and Applications, ed. W. S. C. Chang, pages 52 and 54 cited and relied upon, available to public Aug. 1, 1963.

Crocker et a1. Stimulated Emission in the Far Infrared, Nature, vol. 201, Jan. 18, 1964, pp. 250-251.

Robb et al. Interferometric Observations on Far Infra-red Stimulated Emission Sources, Nature, vol. 202, Apr. 11, 1964, pp. 169-170.

Mathias et a1. Stimulated Emission in the Far Infrared From Water Vapor and Deuterium Oxide Discharges, Physics Letters, vol. 13, November 1964, pp. 35-36.

RONALD L. WIBERT, Primary Examiner 

